Linear motion device comprising a deflection assembly having a single deflection passage

ABSTRACT

A linear motion device has a first assembly and a second assembly which is linearly movable relative to the first assembly, in which at least one first rolling surface which extends in a longitudinal direction is provided on the first assembly, the first rolling surface being located opposite a second rolling surface provided on the second assembly, and in which a row of rolling elements is located between the first and second rolling surfaces, and in which a return passage that is substantially parallel to the first rolling surface is provided in the first assembly, the return passage being connected at either end via a curved deflection passage to the first rolling surface such that rolling elements are transferred, thereby enabling the rolling elements to circulate endlessly, and in which the first assembly includes at least one deflection assembly that may be installed as a whole, and that includes a single deflection passage, and the return passage is provided directly and completely in a separate first body of the first assembly, and the deflection assembly is fastened to the first body via a single, separate fastening bolt that is installable from one side, the fastening bolt being located in the region of the center of curvature of the assigned, curved deflection passage.

CROSS-REFERENCE TO A RELATED APPLICATION

The invention described and claimed hereinbelow is also described inGerman Patent Application DE 10 2009 009 006.1 filed on Feb. 16, 2009.This German Patent Application, whose subject matter is incorporatedhere by reference, provides the basis for a claim of priority ofinvention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention relates to a linear motion device. Linear motiondevices of that type are known, e.g., as bearing rail guides or rollerrail guides, in which case the first assembly is the guide carriage, andthe second assembly is the guide rail. However, the present invention isalso usable in a linear module, in which a linear guide having anassigned drive device is integrated to form one assembly.

JP 64-12129 A makes known a linear motion device in the form of a rollerrail guide. According to FIGS. 1a and 3a of JP 64-12129 A, the linearmotion device includes a first assembly in the form of a guide carriage2, and a second assembly in the form of a guide rail 5, which arelinearly movable relative to one another. A total of four first rollingsurfaces 15 is provided on the first assembly, each of which is oppositea second rolling surface 11a; 11b on the second assembly. A row ofroller-shaped rolling elements that may circulate endlessly in the firstassembly is situated between the aforementioned rolling surfaces. Forthis purpose, a total of four return passages that are parallel to thefirst rolling surfaces is provided in the first assembly. The returnpassages are connected via a curved deflection passage such that rollingelements are transferred. The deflection passage and the return passageare each provided in a deflection assembly that may be installed as awhole on first body 16, the deflection assembly being accommodated inbores 14 of the body.

The deflection assembly is depicted in greater detail in FIG. 3b of JP64-12129 A. It includes two deflection parts 20u; 20l which areseparated from one another in a parting plane that extends through themidpoint trajectory of the circulating rolling elements, and so eachdeflection part is designed in the shape of a half shell. Eachdeflection part includes a first section 1 in which curved deflectionchannel 22 is provided, and a tubular second section 18 in which thereturn passage is provided.

In order to fasten the deflection assembly to the first body, twomutually assigned deflection parts are assembled to form one deflectionassembly, the tubular section of which is slid into the assigned bore ofthe first body. The deflection assembly is therefore retained by thetubular section on the first body. The disadvantage of this embodimentis that a great deal of space is required in the longitudinal directionin front of and behind the first body in order to install the deflectionassembly. This space is typically unavailable, in particular in linearmodules.

A linear module is known, e.g., from DE 10 2006 007 067 A1. In thatpublication, allowances are made for the tight spaces by the fact thatthe deflection assembly may be fastened to the table assembly only fromthe bottom. Accessibility from the top is still required, however, sothat the rivet pins (no. 34 in FIG. 2 of DE 10 2006 007 067 A1) maybecome plastically deformed in order to fasten the deflection assemblyto the table. Moreover, DE 10 2006 007 067 A1 is equipped with an “open”return, in which an open return passage on the first body is covered bythe deflection assembly. The result is much more noise as compared tothe closed return mentioned in JP 64-12129 A since the returning rollingelements strike plastic on the deflection assembly and cause it tooscillate, thereby generating sound. The fact that the cover of thereturn channel is provided on the deflection assembly has thedisadvantage that the latter may only be used in conjunction with aspecified length of the first rolling surface. The deflection assemblymay therefore not be used in different embodiments of linear motiondevices that include first rolling surfaces having different lengths.The related deflection assemblies may therefore be manufactured only insmall quantities and are therefore expensive. This is unfavorable inparticular since the related plastic injection molding tools are veryexpensive, and are particularly suited for use to produce largequantities.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a linear motiondevice, the deflection assembly of which may even be installed in tightspaces. In particular, it should be possible to install the deflectionassembly even when the installation location is only accessible from oneside. Moreover, it should also be possible to create the assignedfastening contours only from this one installation side. In addition,the deflection assembly should be usable in many different embodimentsof linear motion devices. Furthermore, the linear motion device shouldbe particularly quiet.

According to the independent claim, this object is attained by the factthat the return passage is provided directly and completely in aseparate first body of the first assembly, in which case the deflectionassembly is fastened to the first body via a single, separate fasteningbolt that is installable from one side, the fastening bolt being locatedin the region of the center of curvature of the assigned, curveddeflection passage. The return passage is formed entirely in the firstbody, i.e., in the form of a closed return, in order to obtain thedesired low noise level. It is simultaneously provided in the first bodyin order to eliminate the return tube described in JP 64-12129 A. Viathis measure, the deflection assembly may now also be used inconjunction with rolling surfaces having different lengths. Anotherfastening is required as a result. It is realized using a single,separate fastening bolt that is installable from one side. A screw boltis envisioned, in particular, for use in this case. It may be screwed infrom one side, and the assigned thread may be cut on this same side. Ablind rivet may also be used, however. Likewise, its fastening bore maybe bored from the installation side. The purpose of using a singlefastening means is to keep assembly simple. The fastening bolt musttherefore be sufficiently strong. The space required for this isavailable in the center of curvature of the curved deflection channel.

The deflection assembly may include a first and second deflection part,the parting plane of which is defined by the midpoint trajectory of therolling elements in the deflection passage, in which case the fasteningbolt extends through both deflection parts and is situatedperpendicularly to the parting plane. The deflection assembly must bedivided into two deflection parts so that they may be designed largelyfree of undercuts, thereby making it possible to manufacture them usingappropriate plastic injection molds. Via the proposed placement of thefastening bolt, the deflection assembly is fastened to the first body,and the first and second deflection parts are held together by thefastening bolt.

The deflection assembly may be accommodated in a deflection recesslocated on the side of the first body, the deflection recess beingadapted to the deflection assembly such that the deflection assembly issubstantially entirely prevented from rotating. Given that thedeflection assembly is installed on the first body only via a singlefastening bolt, there is a risk that it will rotate about the axis ofthe fastening bolt. This risk is ruled out via the deflection recess. Itshould be noted that it is definitely desirable for the deflectionassembly to be able to rotate slightly in the deflection recess in orderto compensate for tolerances. The deflection assembly is preferablyaccommodated in the deflection recess such that it is fully recessed andis therefore protected against damage. Given that the deflection recessis located on the side of the first body, it may be formed on theaforementioned installation side, e.g., via milling.

The first rolling surface may be provided on a separate, first rollingsurface part that is supported on the first body, the first rollingsurface part extending in the longitudinal direction beyond the firstbody and thereby engaging in the first deflection part and the assignedsecond deflection part. It is known, e.g., from aforementionedpublication DE 10 2006 007 067 A1, to design the rolling surfaces of alinear motion device on a separate rolling surface part that istypically composed of hardened roller bearing steel. The first body maytherefore be made of a softer material, such as aluminum, which issubstantially less expensive to machine. Via the proposed engagement ofthe rolling surface part in the deflection assembly, it is ensured thatthe first rolling surface transitions substantially projection-free intothe curved deflection passage, thereby ensuring smooth running of therolling elements.

The rolling elements may be balls, and the first rolling surface parthas a V-shaped cross section that includes a first V-leg and a secondV-leg, the first V-leg engaging in the first deflection part, and thesecond V-leg engaging in the second deflection part. The use ofspherical rolling elements in conjunction with a V-shaped rollingsurface part is known from DE 10 2006 007 067 A1. The purpose of theproposed engagement in both deflection parts is to attain a particularlygood orientation between the first rolling surface and the curveddeflection passage, it being possible to manufacture the individualdeflection parts simultaneously and substantially projection-free.

A separate transfer part may be provided that engages in the curveddeflection passage and in the adjacent return passage, the transfer partincluding a deformable passage that connects the deflection passage tothe return passage. The purpose of the transfer part is to compensatefor tolerance-induced displacement between the curved deflection passageand the return passage. This is accomplished via the deformable passagewhich may deform in order to compensate for the aforementioneddisplacement. Since the deformation is minimal, the interference in therunning of the rolling elements is minimal. The engagement of thetransfer part in the curved deflection passage and the return passagemay easily be designed such that no projections exist that interferewith the running of the rolling elements.

At least one separate, first lubricating oil storage body may beprovided that has a constant cross sectional shape, and is enclosed bythe first deflection part and the assigned second deflection part, thefirst lubricating oil storage body extending via at least oneapplication section into the assigned deflection passage, therebyenabling it to establish lubricating contact to the rolling elements.The first lubricating oil storage body may be, e.g., an open-cell foamor a felt. The first lubricating oil storage body is preferablymanufactured, cost-favorably, of a panel-type material using water-jetcutting, and so the oil storage body has a constant cross-sectionalshape. The problem typically exists that it is not possible to form asuitable application section using water-jet cutting since theapplication section is substantially smaller—narrower, inparticular—than the storage section. In the deflection assemblyaccording to the present invention, however, it is possible toaccommodate only one lubricating oil storage body having a limited widththat substantially corresponds to the diameter of the rolling body. Itis therefore possible to easily form the application section on the oilstorage body merely by using water-jet cutting. In addition, theproposed design is particularly cost-favorable since the chamber that isrequired for the first lubricating oil storage body may be created inthe deflection assembly at no additional cost.

The first lubricating oil storage body may be directly connected to aseparate, second lubricating oil storage body in alubricant-transferring manner, the second lubricant storage body havinga constant cross-sectional shape that is adapted to the cross-sectionalshape of the second rolling surface and that touches the second rollingsurface; the cross-sectional planes of the first and second lubricatingoil storage bodies are oriented perpendicularly to one another. Thesecond lubricating oil storage body is used to lubricate the secondrolling surface, thereby simultaneously functioning as a stripper thatwipes foreign objects off of the second rolling surface and preventsthem from coming in contact with the rolling elements. These functionsshould also be realized via a lubricating oil storage body that is cutout of a panel-type material and therefore has a constantcross-sectional shape. This is possible only when two lubricating oilstorage bodies are present that are oriented perpendicularly to oneanother. Via the mutual contact of the lubricating oil storage bodies,the entire supply of lubricating oil is made available equally for bothlubricating functions, and is supplied as needed. The service life ofthe lubricating device is increased as a result.

A stripper plate may be formed as a single piece exclusively with thefirst deflection part, which is situated with slight, equidistantclearance from the second rolling surface, the stripper plate supportingthe second lubricating oil storage body against bending. The mainpurpose of the stripper plate is to remove coarse contaminants from thesecond rolling surface. The stripper plate is provided on only one ofthe two deflection parts, so that it may be adapted to the secondrolling surface as exactly as possible. This would not be reliablyensured in the case of a two-component design, due to the expected jointdisplacement between the two halves of the stripper plate. Furthermore,the stripper plate is situated such that it has a stabilizing effect onthe second lubricating oil storage body while it performs the strippingfunction. The second lubricating oil storage body is preferably composedof open-cell foam and therefore has only minimal stiffness. At the sametime, it rubs via a large contact surface against the second rollingsurface, thereby producing relatively great frictional forces that maycause the second lubricating oil storage body to bend. This bending maybe prevented by the stripper plate.

A lifting projection may be provided exclusively on the first deflectionpart, via which the rolling elements may be lifted away from the secondrolling surface and transferred to the assigned deflection passage. Thelifting projection must be adapted to the second rolling surface asexactly as possible so that it may lift the rolling elements off of thesecond rolling surface with minimal interference. This may be easilyensured given that the lifting projection is formed as a single piece ononly one of the deflection parts. In an alternative two-component designthat is likewise feasible, and in which half of the lifting projectionis provided on one of the two deflection parts, it is expected thatjoint displacement would occur, however.

The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a linear motion device according tothe present invention;

FIG. 2 shows a cross section of the linear motion device depicted inFIG. 1; the cutting plane is labeled A-A in FIG. 1;

FIG. 3 shows a perspective view of the first assembly of the linearmotion device depicted in FIG. 1;

FIG. 3 a shows a perspective partial view of a second embodiment of thefirst assembly depicted in FIG. 3;

FIG. 4 shows a perspective view of the drive assembly of the linearmotion device depicted in FIG. 1;

FIG. 5 shows a perspective view of the second assembly of the linearmotion device depicted in FIG. 1;

FIG. 6 shows a perspective view of a rolling element circuit without theenclosing first assembly;

FIG. 7 shows an exploded view of the deflection assembly of the rollingelement circuit depicted in FIG. 6;

FIG. 8 shows a perspective view of the transfer part depicted in FIG. 7;

FIG. 9 shows a cross section of a return passage with the transfer partinserted;

FIG. 10 shows a perspective view of a second embodiment of thedeflection assembly;

FIG. 11 shows an exploded view of a third embodiment of the deflectionassembly;

FIG. 12 shows a perspective view of a second embodiment of the transferpart;

FIG. 13 shows a longitudinal cross-section of the linear motion devicein the region of the transfer part depicted in FIG. 12; and

FIG. 14 shows a cross-sectional view of the linear motion device in theregion of the first and second rolling surface parts.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a linear motion device 10, according to the presentinvention, in the form of a linear module. The linear motion deviceincludes a first assembly 30 in the form of a housing that extends in alongitudinal direction 11. Furthermore, a second assembly 60 is providedin the form of a table part, which is movable longitudinally relative tofirst assembly 30. Second assembly 60 includes a second body 70 which iscomposed of aluminum, on front end 12 of which a fastening plate 82 isprovided that is always located ahead of the front end of first assembly30 regardless of the position of the second assembly. Fastening plate 82is a flat panel composed of aluminum, which, similar to second body 60,includes various fastening means 81 in the form of threaded bores 83 andthrough bores 84, thereby enabling fastening means 81 to be fastened toa higher-order assembly (not depicted).

First assembly 30 includes a first body 40 which is likewise composed ofaluminum. Through bores 42 are provided, as fastening means, in firstbody 40, thereby enabling first assembly 30 to be fastened to alower-order assembly (not depicted). Since fastening means 42 of firstassembly 30 are partially covered by second assembly 60, variouscontinuous installation bores 76 are provided in the latter, via whichscrew bolts may be inserted into through bores 42 in first assembly 30.

A stripper plate 62, which is composed of steel sheet, is installed viafastening screws 62 a on rear end 13 of second body 70. Stripper plate62 is situated close to first body 40 with minimal clearance, therebysubstantially preventing foreign objects from entering the space betweenfirst assembly 30 and second assembly 60. In addition, stripper plate 61is used to close a magnet recess 77 located in the end face (depicted ina basic schematic manner) of second body 70, in which a permanent magnet63 (depicted in a basic schematic manner) is accommodated. The magneticfield of permanent magnet 63 may be detected by one or more sensors 33which may be installed in any longitudinal position in an undercutsensor groove 41 which extends in longitudinal direction 11. As aresult, one or more positions of second assembly 60 relative to firstassembly 30 may be detected by a higher-order control device (notdepicted).

A drive assembly 90 is provided at rear end 13 of first body 40, usingwhich second assembly 60 may be moved relative to first assembly 30.However, FIG. 1 only shows gearbox housing 91 of drive assembly 90 whichwill be explained in greater detail with reference to FIG. 4.

FIG. 2 shows a cross section of linear motion device 10. Shown is theentire U-shaped design of second body 70 including a base 71 and twoU-legs which extend perpendicularly away therefrom. A second rollingsurface part 61 is provided on each of the opposite inner sides of theU-leg. Second rolling surface part 61 is a profiled element that extendsin the longitudinal direction, and that has a constant, substantiallyV-shaped cross section. Second rolling surface part 61, which iscomposed of hardened roller bearing steel, is provided on the inner sideof the V shape with a second rolling surface 61 a that is designed witha cross-sectional profile in the shape of a Gothic arch, and sospherical rolling elements 15 touch second rolling surface 61 a at twopoints in a known manner. A first rolling surface part 31, which isdesigned identically to second rolling surface part 61 except in termsof length, is situated opposite second rolling surface part 61. Rollingelements 15 may therefore roll between first rolling surface 31 a andsecond rolling surface 61 a, and so second assembly 60 is supported onfirst assembly 30 in a longitudinally moveable manner. First body 40 andsecond body 70 are each fabricated from a raw part that is manufacturedof aluminum via extrusion, and the cross-sectional profile formed duringextrusion largely corresponds to the cross-sectional profile shown inFIG. 2. Reference is made below to the geometries that are attained viamachining after the extrusion process is carried out. Reference is mademainly to accommodating recesses 48; 74, in which first rolling surfaceparts 31 and second rolling surface parts 61 are accommodated in aform-locked manner. Accommodating recesses 48; 74 must be adaptedexactly to assigned rolling surface parts 31; 61, and they must be verystraight so that the rolling guidance functions in a stiff and accuratemanner. They were therefore formed in the related raw part via milling.

A return passage 50, which is manufactured via extrusion without anypost-machining, is assigned to every first rolling surface 31. Returnchannel 50, the cross-sectional shape of which is described in greaterdetail with reference to FIG. 9, is connected at either end via a curvedpassage (number 125; FIG. 7) to assigned first rolling surface 31 a,thereby enabling rolling elements 15 to circulate endlessly.

First rolling surface part 31, which is shown on the right in FIG. 2, isaccommodated on an adjustment section 45 of first body 40, which may bedisplaced relative to base section 44 of first body 40, on which thefastening means (number 42; FIG. 1) for the lower-order assembly areprovided, thereby enabling the preload of the rolling guidance to beadjusted. To this end, adjustment section 45 is connected as a singlepiece to base section 44 via two flexurally resilient segments 47 thatextend in the longitudinal direction. Adjustment section 45 includes anadjusting means in the form of a screw bolt 35 that is screwed into athread 46 (depicted in a basic schematic manner) of adjustment section45. Since screw bolt 35 is covered by second assembly 60, an opening(number 43, FIG. 1) is provided in the latter, thereby enabling screwbolt 35 to be adjusted, e.g., using an Allen key. End face 35 a of thescrew bolt bears via a separate rectangular steel strip 34 against basesection 44. Steel strip 34 is needed to prevent screw bolt 35 fromplastically deforming the soft aluminum of first body 40, which wouldresult in a reduction in the preload on rolling elements 15. Theaforementioned flexurally resilient segments 47 are each situatedparallel to U-legs 72 of second assembly 60, and the screw axis of screwbolt 35 is oriented perpendicular thereto, thereby providing anadjustment device that is suitable for adjusting the preload.

It is also pointed out that first body 40 is situated opposite to secondbody 70 with slight equidistant clearance, thereby resulting in a narrowsealing gap 19 between them that prevents foreign objects from enteringthe space between these parts. In particular, foreign objects should beprevented from reaching rolling elements 15 since this may cause damageif the foreign objects enter the space between rolling elements 15 andassigned rolling surfaces 31 a; 61 a. To make it even more difficult forforeign objects to enter, sealing gap 19 is provided with a directionchange 20 starting at outer surface 14 of linear motion device 10.Reference is also made here to reinforcing rib 78 on second body 70,which is used to increase the bending resistance of second body 70.Reinforcing rib 78 engages in rib recess 52 in first body 40, and soaforementioned narrow sealing gap 19 is also present in this region.

FIG. 2 also shows the T-shaped cross section of undercut sensor groove41.

Reference is likewise made to push tube 80 which will be described ingreater detail with reference to FIG. 5. Push tube 80 is accommodatedwith slight clearance in a nut recess 56 of first body 40.

FIG. 3 shows first assembly 30. First body 40 of first assembly 30 isdivided into a first longitudinal section 40 a and a second longitudinalsection 40 b which abut one another directly. Endlessly circulatingrolling elements 15 described above are located in second longitudinalsection 40 b which is located on front end 12 of first assembly 30. FIG.3 shows, in particular, the four circulatory assemblies 120, each ofwhich includes a single, curved deflection passage (number 125; FIG. 7)which connects assigned first rolling surface (number 31 a; FIG. 2) toassigned the return passage (number 50; FIG. 2). Deflection assemblies120, which are identical in design, are configured such that they may beinstalled from a single installation side 32, and the related fasteningcontours 53 in first body 40 may also be created exclusively frominstallation side 32. Installation side 32 is the top side—as shown inFIG. 3—of first assembly 30. A deflection recess 53, which is formedusing an end mill, is provided for each deflection assembly, as thefastening contour in first body 40. It should be noted here that thereturn passage (number 50; FIG. 2) extends along the entire length ofthe extruded raw part; the remainder 50 b of the return passage, whichdoes not perform a function in first longitudinal section 40 a of firstbody 40, is shown in FIG. 2. Each of the four deflection assemblies 120is fastened to first body 40 using a single screw bolt 131 which mayalso be screwed in from aforementioned installation side 32, and theassigned threaded bore may likewise be tapped from installation side 32.This embodiment of the rolling element return makes it possible to useone design of deflection assembly 120 in many different designs oflinear motion devices 10.

Above-described adjustment section 45 of first body 40 is located on theright side in FIG. 3. It is shown, in particular, that three screw bolts35 are provided for used to adjust the preload on the rolling elements.Transverse slot 54 and longitudinal slot (number 165; FIG. 2) are usedto separate adjustment section 45 from base section 44 of first body 40,thereby ensuring that its adjustment motion is not hindered.

A separate closing plate 36, which is composed of steel sheet, isprovided on front side 12 of first assembly 30. Closing plate 36 isdesigned to have slight, equidistant clearance from the second body(number 70; FIG. 2). Reference is made to stop section 36 b of closingplate 36, which partly extends beyond first body 40, thereby enabling itto function as an end stop for the second assembly. To this end, a stopsurface (number 79; FIG. 5) is provided on the second body, whichextends transversely to the longitudinal direction, thereby ensuringthat it may come to bear against stop section 36 b. The stop surface iscreated by milling the end faces of the U-legs of the raw part of thefirst body accordingly. Reference is likewise made to stripperprojection 36 a which is adapted to the second rolling surface (number61 a; FIG. 2) of second assembly 60 with very little clearance. It isused to remove foreign objects such as metal chips from the secondrolling surface, thereby preventing them from entering the rollingelement circuit, where they may cause damage.

A motor recess 55 for accommodating the electric motor (number 101; FIG.4) of the drive assembly is provided in first longitudinal section 40 aof first body 40. Motor recess 55 is created entirely via milling sincethe flexurally resilient segments (number 47; FIG. 2) of the adjustmentmechanism, which are used to adjust the preload of the rolling guide,are located at this point in the raw part of first body 40. The outersurface, of first body 40 is not machined in first longitudinal section40 a, starting at the extruded raw part. This contour therefore had tobe milled away in second longitudinal section 40 b in order to providethe receiving recess (number 48; FIG. 2) in the first rolling surfacepart.

A nut recess 56 is provided next to motor recess 55, and extends alongthe entire length of first assembly 30; nut recess 56, together withmotor recess 55, forms a drive cavity of the drive assembly (number 90;FIG. 4). Nut recess 56 is used to receive the threaded spindle (number95; FIG. 4) of the drive assembly, and to receive the assigned push tube(number 80; FIG. 5) of the second assembly. Nut recess 56 and motorrecess 55 are located, at least in sections, at the level (number 73;FIG. 2) of the U-legs of the second body, and so the linear motiondevice has a particularly low overall height.

Motor recess 55 is connected via an air exchange recess 57 to nut recess56, and all aforementioned recesses are covered by the drive assembly(number 90; FIG. 1) in an air-tight manner. Therefore, the air that isdisplaced when the second assembly moves inward due to the motion of thenut and the push tube (number 80; FIG. 5) in nut recess 56 flows via airexchange recess 57 into motor recess 55, past the electric motor (number101; FIG. 4), and via transverse slot 54 to the outside. When the secondassembly moves outward, the air flows in the opposite direction. Theelectric motor is cooled by the air blowing past it, thereby making itpossible to use a particularly small electric motor with a high powerdensity.

FIG. 3 a shows a second embodiment 30 a of the first assembly. Itdiffers from first embodiment 30 shown in FIG. 3 only in thatadjustable, first rolling surface part 31 is not supported via a centrallongitudinal section 31 c on first body 40. This measure was implementedto prevent a backup of the rolling elements due to the relatively longfirst rolling surfaces. The long length of the first rolling surfaceswas selected so that first assembly 30 a may stiffly support high torqueloads.

Aforementioned central longitudinal section 31 c is formed by millingaway body 40 nearly entirely in this region, thereby forming a firstadjustment section 45 a and a second adjustment section 45 b—which haveclearance between them—of first main body 40. Therefore, there isabsolutely no material left in the central longitudinal section 31 cbehind the first rolling surface part that could support it; a gap 31 dtherefore exists in central longitudinal section 31 c between firstrolling surface part 31 and first body 40. Since first rolling surfacepart 31 has only relatively minor stiffness, rolling elements 15 thatroll there are merely subjected to a minor load, thereby enabling themto be displaced in a gliding manner when rolling elements become backedup, thereby immediately eliminating the back-up of rolling elements.

First adjustment section 45 a and second adjustment section 45 b areconnected to one another as a single piece only via return tube 51, inwhich return passage (number 50; FIG. 2) is located. Since the walls ofreturn tube 51 are relatively thin, return tube 51 has a relativestiffness, thereby enabling first adjustment section 45 a and secondadjustment section 45 b to be adjusted largely independently of oneanother, in order to adjust the preload of the roller guidance. It hasproven favorable to provide first adjustment section 45 a and secondadjustment section 45 b with only one adjustment means each, in the formof a screw bolt, since this makes it possible to adjust the preload inthe quickest manner possible.

For the rest, the design of second embodiment 30 a of the first assemblyis identical to that of first embodiment 30. This applies, e.g., tomilled-out dividing section 58 a, via which a dividing gap 58 betweenadjustment section 45; 45 a; 45 b and base section 44 of first body 40is formed, thereby ensuring that the adjustment section has the desiredadjustability. FIG. 3 a also shows fastening screws 37, via whichclosing plate 36 is fastened to first body 40. Finally, reference islikewise made to tapped bores 42, using which first assembly 30; 30 amay be fastened to a higher-order assembly.

FIG. 4 shows drive assembly 90 which may be fastened as a whole to therear longitudinal end of the first body; gearbox housing (number 91;FIG. 1) is not shown, for clarity. Drive assembly 90 includes electricmotor 101 and threaded spindle 95, axes of rotation 95 a; 101 a of whichare oriented parallel to one another. Electric motor 101 and threadedspindle 95 are connected in a rotationally driving manner via an endlesstoothed belt 94; the smaller, first toothed belt pulley 92 is located onelectric motor 101, and the larger, second toothed belt pulley 93 islocated on threaded spindle 95. Electric motor 101 is fastened viafastening screws 105 to a motor plate 104. This, in turn, may befastened in various transverse positions to gearbox housing (number 91;FIG. 1), thereby making it possible to adjust the tension of the toothedbelt required during operation by displacing electric motor 101. Theappropriate position of motor plate 104 is secured using cylindrical pin106 which engages in gearbox housing (number 91; FIG. 1) in aform-locked manner. Electric motor 101 is equipped with a rotary encoder103, the signal of which is forwarded via electrical line 102 to ahigher-order control (not depicted). Via electrical line 102, electricmotor 101 is also supplied with electric current via higher-ordercontrol. Furthermore, electric motor 101 is equipped with a single motorhousing 101 b, and so the cooling air described above flows betweenmotor housing 101 b and motor recess (number 55; FIG. 3). This preventsforeign objects that have been drawn in via the cooling air fromreaching the interior of electric motor 101.

Threaded spindle 95 includes a bearing part 97 and a threaded part 96.Threaded part 96 is a section of a ball screw spindle which ismanufactured using a thread rolling method, and which is thereforeprovided with one or more thread turns 95 b along its entire length. Inthread rolling, threaded spindles having a length of several meters areusually manufactured. They are cut to the desired length to formthreaded part 96, without any further machining being performed.

Bearing part 97 is connected to threaded part 96 via a clamping section97 b on bearing part 97, which acts directly on thread turns 95 b ofthreaded part 96. For reasons of cost, thread turns 95 b were notremoved in the clamping region since sufficient clamping force isattained even without this measure. Clamping section 97 b of bearingpart 97 includes two clamping jaws that are separated from one anothervia a slot 97 c; a clamping screw 100 extends through slot 97 c in orderto generate the desired clamping force.

Second toothed belt pulley 93 is designed as a separate component, iscomposed of aluminum, and is non-rotatably connected to bearing part 97which is made of steel. Furthermore, a radial deep-groove ball bearing98 is provided on bearing part 97, and is fixedly clamped to bearingpart 97 via its inner ring using a groove nut 99. Outer ring 98 a ofradial roller bearing 98 is secured in the gearbox housing (number 91;FIG. 1). Threaded spindle 95 is equipped with only one pivot bearing.Accordingly, the present radial roller bearing is designed to includetwo rows, thereby ensuring that it has the required loadability. Segment97 a remaining on bearing part 97 may be used, e.g., to install a brake,using which threaded spindle 95 may be brought to a standstill.

FIG. 5 shows second assembly 60 in the form of the table part; thefastening part (number 82; FIG. 1), which is located on frontlongitudinal end face 12 of second body 70, is not shown, for clarity.Second assembly 60 includes second body 70 which extends via a U-shapedcross section in longitudinal direction 11. Furthermore, second assembly60 includes a push tube 80 which is designed separate from second body70 and includes a connecting segment 80 b which is formed as a singlepiece therewith, and via which it is screwed to second body 70. In therearmost position of second assembly 60, connecting segment 80 b, whichis provided on the front longitudinal end of push tube 80, engages insegment recess (number 59; FIG. 3 a) of the first assembly, and pushtube 80 simultaneously extends through its push tube opening (number 36c; FIG. 3 a). Push tube 80 is composed of aluminum and is manufacturedvia extrusion; the front, end-face opening of push tube 80 is closedusing a separate stopper 87 which is composed of plastic.

A threaded nut 86 in the form of a recirculating ball nut is mounted onrear longitudinal end 13 of the push tube, and is engaged in screw-typemanner with the threaded spindle (number 95; FIG. 4) of the driveassembly. Threaded nut 86 is designed as a screw-in nut, i.e., itincludes an internal thread on its front end, which is screwed onto acorresponding external thread on push tube 80. To ensure that thetightening torque of the screw connection is sufficient, threaded nut 86and push tube 80 are each provided with a pair of opposing key surfaces86 b; 80 a.

Furthermore, a gap seal 85, which is accommodated in a circumferentialgroove of push tube 80, is provided on rear end 13 of push tube 80. Gapseal 85 is interrupted only once in the circumferential direction,thereby enabling it to be easily installed on push tube 80. The purposeof gap seal 85 is to seal the nut recess (number 56; FIG. 3) at thispoint in a substantially air-tight manner in order to generate theabove-described cooling-air flow. Gap seal 85 therefore bearssubstantially tightly against the nut recess.

Threaded nut 86 is provided with a known end seal 86 a, which bearsagainst the threaded spindle (number 95; FIG. 4) only on the side facingaway from the push tube. Threaded nut 86 is open on the opposite end,thereby resulting in a connection to the interior of push tube 80, whichis filled with lubricating grease. In this manner, it is ensured thatthreaded nut 86 will be lubricated throughout its entire service life.

FIG. 5 also shows that reinforcing rib 78 and second rolling surfaceparts 61 extend along the entire length of second assembly 60. Alongitudinal displacement of second rolling surface parts 61 in assignedreceiving recess (number 74; FIG. 2) is prevented by stripper plate 62and the fastening plate (number 82; FIG. 1).

FIG. 6 shows a rolling element circuit 16; the enclosing first assemblyis not shown, for clarity. Rolling element circuit 16 encloses a row ofspherical rolling elements 15, which is configured in the form of anendless loop. Load-bearing rolling elements 17 shown at the front inFIG. 6 roll on first rolling surface part 31 which engages via each ofthe two ends in a deflection assembly 120, in each of which one curveddeflection passage (number 125; FIG. 7) is provided. For this purpose,every first rolling surface part 61 must extend past the first body(number 40; FIG. 3) in the longitudinal direction at both ends.Returning rolling bodies 18 shown at the rear in FIG. 6 roll in thereturn passage (number 50; FIG. 2) which is provided directly in thefirst body of the first assembly. To attain the best possibleorientation between a deflection passage 120 and the assigned returnpassage, the former are provided with finger-type extensions 141 thatengage in the return passage.

FIG. 7 shows an exploded view of deflection assembly 120. Deflectionassembly 120 includes a first deflection part 121, and a seconddeflection part 122, which is composed of plastic; deflection parts 121and 122 are designed largely as mirror-images relative to parting plane123. Deflection parts 121; 122 both limit curved deflection passage 125which connects the first rolling surface (number 31 a; FIG. 2) to thereturn passage (number 50; FIG. 2). Curved deflection passage 125 has acircular cross-sectional shape that is sized such that the sphericalrolling elements may pass through it with minimal play.

A lifting projection 128, via which the rolling elements are lifted awayfrom the first rolling surface and transferred to the curved deflectionpassage, is provided on the end of curved deflection passage 125 that isassigned to the first rolling surface. Lifting projection 128, which isknown per se, is formed exclusively on first deflection part 121,thereby enabling it to be situated at a particularly close distance tothe first rolling surface. The position of deflection assembly 120relative to the first rolling surface is defined via orientation recess127, into which the corresponding first rolling surface part engages.One half of orientation recess 127 is provided on first deflection part121, and the other half is provided on second deflection part 122, andeach half is assigned to a V-leg (number 31 e; 31 f in FIG. 11) of thefirst rolling surface part.

A separate transfer part 140, which is composed of plastic and will bedescribed in greater detail with reference to FIGS. 8 and 9, is providedon the end of the curved deflection passage assigned to the returnpassage. Transfer part 140 is accommodated in a conical recess 126, thesmallest diameter 126 a of which is adapted to the assigned section oftransfer piece 140 substantially without play. Due to the conical shapeof aforementioned recess 126, some open space is available to flexibletube 150 of transfer part 140 in the transverse direction, therebyenabling it to bend accordingly in order to compensate for displacementbetween curved deflection passage 125 and the return passage. For thispurpose, it engages via three finger-type extensions 141 into theadapted grooves (number 50 c; FIG. 9) of the return passage. Transferpart 140 bears via end face 150 a of flexible tube 150 against anassigned end face (number 53 a; FIG. 3) of the first body, and so it isretained substantially without play in conical recess 126.

An opening 124 is formed in center of curvature 125 a of the curveddeflection passage in first deflection part 121 and in second deflectionpart 122, through which a fastening bolt 131 in the form of a screw boltextends. In this manner, deflection parts 121; 122 are fixedlyinterconnected, and entire deflection assembly 120 is fastened to thefirst body. Instead of screw bolt 131, a blind rivet or a similarfastening bolt may be used, for instance, which may be installedexclusively from one side, namely the installation side (number 32; FIG.3).

Furthermore, a lubricating system is provided in deflection assembly120, which is formed of a first lubricating oil storage body 132 and asecond lubricating oil storage body 133 which are composed of anopen-cell foam. Lubricating oil storage bodies 132; 133 are each cut outof a panel-type material via water-jet cutting, and so they have theshape of a profiled element having a substantially constant crosssection 132 a; 132 b. First lubricating oil storage body 132 has thelarger volume, which is why it provides the majority of the storagevolume for the lubricating oil. An application section 132 b is formedas a single piece on first lubricating oil storage body 132, and extendsinto curved deflection passage 125, and so the rolling elements passingby run along it, by way of which lubricating oil is transferred fromfirst lubricating oil storage body 132 to the rolling elements.

Second lubricating oil storage body 133 glides directly along the firstrolling surface, thereby lubricating it and removing small dirtparticles from it. The outer contour of stripper section 133 c of secondlubricating oil storage body 133 is adapted exactly to thecross-sectional profile of the first rolling surface. Cross-sectionalplanes 132 a; 133 a of first and second lubricating oil storage bodies132; 133 are oriented perpendicularly to one another; second lubricatingoil storage body 133 includes a projection 133 b, via which it touchesthe first lubricating oil storage body, thereby enabling lubricating oilto be transferred from the first lubricating oil storage body to thesecond lubricating oil storage body. The intention is to distribute theentire stored quantity of lubricating oil onto the two lubricatingpoints as needed. This may be attained by sizing aforementionedprojection 133 b in a suitable manner, in particular its contact facesto first lubricating oil storage body 132. Reference is likewise made tostripper plate 129, via which the relatively thin, second lubricatingoil storage body is supported against bending. Stripper plate 129 isformed at a slight, equidistant distance from the first rolling surface,and, similar to lifting projection 128 which likewise supports thesecond lubricating oil storage body against bending, is formed entirelyon first deflection part 121. Stripper plate 129 may also remove largerforeign objects from the first rolling surface, provided this has notalready been done by the stripper projection (number 36 a; FIG. 3) ofthe closing plate.

FIG. 8 shows transfer part 140 in a greatly enlarged view. Transfer part140 is designed as a single piece, and is made of plastic using aninjection-molding procedure. Transfer part 140 includes a flexible tube150 that has a substantially circular cross-sectional shape, on thefront end of which three identical finger-type extensions 141 arelocated equidistantly around the circumference of bendable tube 150.Finger-type extensions 141 have a U-shaped cross-sectional shape alongtheir entire length, and they include a base 144 from which two U-legs145 each extend at right angles. The end faces of the U-legs form guidesurfaces 143 for the spherical rolling elements that pass throughtransfer part 140. The length of U-legs 145 increases from the free endof finger-type extensions 141 toward the flexible tube, and soaforementioned guide surfaces 143 are slanted relative to the course ofthe return passage. It should be noted that base 144 of finger-typeextensions 141 is oriented parallel to the return passage, and it bearsvia a contact projection 147 directly against the base of the assignedgroove (number 50 c; FIG. 9) in the return passage. Reference is made tothe embodiments described with reference to FIG. 9 in terms of the exactplacement of guide surfaces 143 relative to the return passage.

Flexible tube 150 is provided with a total of six windows 151 in orderto increase its flexural elasticity. The flexible tube therefore forms aflexible passage 140 a for the rolling elements, via which a possibledisplacement between the return passage and the curved deflectionpassage may be compensated for. Segments 152 formed between windows 151are extensions of U-legs 145 of finger-type extensions 141, and so guidesurfaces 143 provided there for the rolling elements may be continuedwithout interruption on segments 152 a.

FIG. 9 shows a cross section of a return passage 50 with transfer part140 inserted. Return passage 50 has a substantially circularcross-sectional shape that is adapted to rolling elements 15 with slightplay. Three grooves 50 c are distributed equidistantly around thecircumference of return passage 50. Grooves 50 c extend along the entirelength of return passage 50 since it and grooves 50 c are created duringthe extrusion of the first body, and they are not machined further. Onefinger-type extension 141 of deflection part 140 is accommodated in eachof the grooves 50 c; grooves 50 c are designed to have slight clearancefrom finger-type extension 141. A contact projection 147 which bearsagainst base 50 d of groove 50 c is provided on base 144 of eachfinger-type extension 140. Grooves 50 c and contact projections 147 arematched to one another such that transfer part 140 is accommodated inreturn passage 50 with slight preload. Width 50 f of grooves 50 c isapproximately 40% of ball diameter 15 a, and so rolling elements 15 arestill guided adequately in return passage 50 at a distance from grooves50 c.

Guide surfaces 143 for rolling elements 15 are shown with their slantedcourse in FIG. 9. The front end of each guide surface is situated so farway 143 a from central axis 50 a of return passage 50 that it is ensuredto be recessed in groove 50 c. It is therefore ruled out that rollingelements 15 that approach from return passage 50 and enter the curveddeflection passage may collide with end face 146 of finger-typeextensions 141.

The rear end of the guide surfaces on the finger-type extensions issituated so far away 143 b from central axis 50 a of return passage 50that it extends out of assigned groove 50 c by a small amount. It istherefore ruled out that rolling elements 15 that approach from thecurved deflection passage and enter return passage 50 may collide withthe end face of the first body (number 53 a; FIG. 3). The aforementionedslight overhang is difficult to see due to its small size in FIG. 9which is drawn to scale.

FIG. 10 shows a second embodiment of deflection assembly 120 a, inwhich, in contrast to first embodiment 120 shown in FIG. 9, finger-typeextensions 141 are designed as a single piece with first deflection part121 and second deflection part 122. The separate transfer part istherefore eliminated in this embodiment, and so second embodiment 120 ais slightly more cost-favorable than first embodiment 120, although theadvantages of the flexible passage (number 140 a; FIG. 8) must beforegone. First embodiment 120 of the deflection assembly, which isotherwise identical to second assembly 120 a, is preferred due to itsadvantages.

FIG. 11 shows a third embodiment 120 b of the deflection assembly, inwhich first rolling surface part 31 is rotatably accommodated indeflection assembly 120 b. To this end, deflection assembly 120 bincludes a separate holding part 134, in which orientation recess 127for the first rolling surface part is provided. As in all otherembodiments of the deflection assembly, rolling surface part 31 isdesigned as a profiled element having a constant cross-sectional shape,and flat longitudinal end faces 31 b are provided on both ends of thefirst rolling surface part. The cross-sectional shape of first rollingsurface part 31 is substantially V-shaped, having a first V-leg 31 e anda second V-leg 31 f. On the outside, holding part 134 is provided with acircular-cylindrical surface 134 a, the longitudinal axis of whichextends through the midpoint of the spherical rolling elements.Circular-cylindrical surface 134 a bears against a modified surface 130of remaining deflection assembly 120 b, and so first rolling surfacepart 31 is rotatable about the midpoint of the rolling elements relativeto deflection assembly 120 b. Via this measure, the same design ofdeflection assembly 120 b may be used in various designs of linearmotion devices. The purpose of the rotatability described above is toaccount for the different spacial conditions in the various linearmotion devices. Nevertheless, first embodiment 120 of the deflectionassembly, which is otherwise identical to third embodiment 120 b of thedeflection assembly, is preferred due to its ease of manufacture.

FIG. 12 shows a perspective view of a second embodiment of transfer part140 b, in which the deformed state according to FIG. 13 is shown. In thenon-deformed state, transfer part 140 b is rotationally symmetrical. Itincludes a thin-walled, circular-cylindrical, closed tube 155, on theend of which a radial ridge 153 is provided, the outer circumferentialsurface of which is also circular-cylindrical in shape. The innersurface of thin-walled tube 155 forms flexible passage 140 a. Transferpart 140 b is composed of plastic, and is manufactured using aninjection-molding procedure.

FIG. 13 shows transfer part 140 b in the installed state. Deflectionassembly 120 is designed in accordance with the first embodiment whichwas described above extensively with reference to FIG. 7, and so it willnot be described again here. In terms of return passage 50, the groovesthat extend in the longitudinal direction were eliminated, and so it hasa circular cross section. Instead, a recess 49, which is adapted toradial ridge 153 of transfer part 140 b, is provided on the end of firstbody 40. Recess 49 is also circular-cylindrical in design and has thesame diameter 126 b as radial ridge 153. Depth 49 a of recess 49 isgreater than width 153 a of radial ridge 153, and so flexible tube 150has a long length and therefore sufficient elasticity.

FIG. 13 shows a case of installation in which a particularly greatalignment error exists between deflection passage 125 and return passage50. The bending-related deformation of flexible tube 150 is thereforeparticularly great. Nevertheless, no notable interferences that couldcreate noise exist in the path of spherical rolling elements.

It is also pointed out that opening width 126 b of conical recess 126 isgreater than opening width 49 b of recess 49. This measure serves tocompensate for the alignment error between recesses 126; 49 which aredirectly opposite one another.

FIG. 14 shows a cross section of linear motion device 10 in the regionof the first and second rolling surface parts 31; 61. In particular, thefigure shows the formation of the placement geometry of first rollingsurface part 31 on first body 40, and of second rolling surface part 61on second body 70; the aforementioned geometries are substantiallypoint-symmetrical about the midpoint of rolling elements 15.Substantially V-shaped rolling surface parts 31; 61 bear via a first leg160 in each case and via their entire area against assigned body 40; 70;an approximately linear contact between rolling surface parts 31; 61 andassigned bodies 40; 70 is provided on second leg 161. For this purpose,a narrow extension 162 is formed on each body 40; 70, each of whichextends along the entire length of assigned rolling surface part 31; 61.Rolling surface parts 31; 61 bear via their flat back sides againstextension 162. The purpose of this measure is to compensate fordeviations in terms of shape between receiving recesses 48; 74 andassigned rolling surface parts 31; 61. In particular, the aim is forrolling surface parts 31; 61 to bear against assigned body 40; 70 in apredictable manner even under unfavorable tolerance conditions, so thatrolling elements 15 run along the entire length of rolling surface parts31; 61 under a substantially constant preload.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in alinear motion device comprising a deflection assembly having a singledeflection passage, it is not intended to be limited to the detailsshown, since various modifications and structural changes may be madewithout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

1. A linear motion device, comprising a first assembly and a secondassembly which is linearly movable relative to the first assembly, inwhich at least one first rolling surface which extends in a longitudinaldirection is provided on the first assembly, the first rolling surfacebeing located opposite a second rolling surface provided on the secondassembly, and in which a row of rolling elements is located between thefirst rolling surface and the second rolling surface, and in which areturn passage that is substantially parallel to the first rollingsurface is provided in the first assembly, the return passage beingconnected at either end via a curved deflection passage to the firstrolling surface such that the rolling elements are transferred, therebyenabling the rolling elements to circulate endlessly, and in which thefirst assembly includes at least one deflection assembly that isinstalled as a whole, and that includes a single deflection passage,wherein the return passage is provided directly and completely in aseparate first body of the first assembly, and the deflection assemblyis fastened to the first body via a single, separate fastening bolt thatis installable via one side, the fastening bolt being located in aregion of a center of curvature of the assigned, curved deflectionpassage.
 2. The linear motion device as recited in claim 1, wherein thedeflection assembly includes a first deflection part and a seconddeflection part, a parting plane of which is defined by a midpointtrajectory of the rolling elements in the deflection passage; thefastening bolt extends through both deflection parts and is situatedperpendicularly to the parting plane.
 3. The linear motion device asrecited in claim 1, wherein the deflection assembly is accommodated in adeflection recess located on a side of the first body, the deflectionrecess being adapted to the deflection assembly such that the deflectionassembly is substantially entirely prevented from rotating.
 4. Thelinear motion device as recited in claim 1, wherein the first rollingsurface is provided on a separate, first rolling surface part that issupported on the first body, the first rolling surface part extending inthe longitudinal direction beyond the first body and thereby engaging inthe first deflection part and the assigned second deflection part. 5.The linear motion device as recited in claim 4, wherein the rollingelements are balls, and the first rolling surface part has a V-shapedcross section that includes a first V-leg and a second V-leg, the firstV-leg engaging in the first deflection part, and the second V-legengaging in the second deflection part.
 6. The linear motion device asrecited in claim 1, wherein a separate transfer part engages in thecurved deflection passage and in the adjacent return passage, thetransfer part including a deformable passage that connects thedeflection passage to the return passage.
 7. The linear motion device asrecited in claim 2, wherein at least one separate, first lubricating oilstorage body is provided that has a constant cross-sectional shape, andis enclosed by the first deflection part and the assigned seconddeflection part, the first lubricating oil storage body extending via atleast one application section into the assigned deflection passage,thereby enabling it to establish lubricating contact to the rollingelements.
 8. The linear motion device as recited in claim 7, wherein thefirst lubricating oil storage body is directly connected to a separate,second lubricating oil storage body in a lubricant-transferring manner,the second lubricant storage body having a constant cross-sectionalshape that is adapted to a cross-sectional shape of the second rollingsurface, and that touches the second rolling surface; cross-sectionalplanes of the first and second lubricating oil storage bodies areoriented perpendicularly to one another.
 9. The linear motion device asrecited in claim 8, wherein a stripper plate is formed as a single pieceexclusively with the first deflection part, and is situated with slight,equidistant clearance from the second rolling surface, the stripperplate supporting the second lubricating oil storage body againstbending.
 10. The linear motion device as recited in claim 8, wherein alifting projection is formed as a single piece exclusively with thefirst deflection part, using which the rolling elements is lifted off ofthe second rolling surface and transferred to the assigned deflectionpassage.